An increase in the understanding of the mechanisms of male-to-female sexual transmission is the long-term goal of this proposal which can be used to facilitate the development of microbicides and therapies designed to treat the early events of HIV infection. Although mucosal T cells and Langerhans cells have been identified as potential early targets of infection in the female genital tract how the virus gains access to these target cells after traversing the epithelial barriers remains a mystery. To gain insights into this process it is being proposed to utilize a new technology that allows the identification of individual virions of HIV in tissue. The Hope Lab has previously validated this system using ectocervical and endocervical tissue explants and bioengineered epithelial culture systems. However, these types of systems only attempt to mimic what takes place in vivo. It is now time to extend these studies to an animal model for female-to-male sexual transmission. The most characterized of these systems is the rhesus macaque model using SIV modified to use the HIV envelope protein (SHIV). The proposal seeks to fund experimentation to characterize the interaction of HIV with the rhesus macaque female genital tract and provide insights into how HIV gains access to target cells in the vaginal mucosa and those cells first infected. These studies will identify portions of the female genital tract that are less efficient as barriers to HIV entering the underlying tissue. They will also identify the potential interaction of HIV with target cells in the vaginal mucosa and possibly give insight into what cells are infected primarily. They may also identify the interaction of HIV with cellular compartments that will provide insights into the mechanisms of how HIV can enter and move within the tissue. HUMAN HEALTH RELEVANCE: Therefore, these proposed studies are highly relevant to the request for applications because a better understanding of the mechanisms of male-to-female sexual transmission can be used facilitate the development of microbicides and therapies designed to treat the early events of HIV infection (peritransmission events).